1. Field of the Invention
The present invention pertains to apparatus for casting. More particularly, the present invention pertains to casting forms for the casting of concrete septic tanks, burial vaults and the like. Even more particularly, the present invention relates to casting forms having collapsible and expandible walls and means for facilitating the collapsing and expansion thereof.
2. Prior Art
The formation of concrete septic tanks burial vaults and other such structures generally contemplates the casting thereof in a "form". The form usually comprises an inner form and an outer form spaced apart from the inner form and into which the casting material, e.g. concrete, is poured.
The outer form is usually a disassembleable rigid structure. The inner form comprises expandible and collapsible side walls and end walls. The inner form also includes a top wall or cover plate which mates with the edges of the walls.
In U.S. Pat. No. 2,807,071, the disclosure of which is hereby incorporated by reference, there is taught casting apparatus of the type under consideration herein. With respect to this apparatus, it has been found, however, that the placement of the cover plate is extremely difficult and not coordinated with the expansion of the side and end walls of the inner form.
The present invention, on the other hand, alleviates this problem. Concommitantly, the present invention also provides improved means for collapsing and expanding the walls of the inner form.